Diet Choices Can Help Environment

While households consider eating more locally to reduce the greenhouse gas emissions associated with food's transport, two Carnegie Mellon researchers recently found that a simple alteration in the average American diet could have an even greater impact on the environment.

Christopher Weber and H. Scott Matthews estimate that by eliminating meat from your diet just one day per week, you would reduce the same amount of greenhouse gas emissions as driving 1,000 miles less per year. Taking that a step further, they say that going entirely vegan would reduce the same amount of emissions as driving 8,000 miles less per year.

Their argument was published in the Environmental Science & Technology journal and has won the award for "Best Paper on Environmental Policy of 2008."

"Where you get your food from is a relevant factor in family food decisions, but what you are eating — and the processes needed to make it — is much more important from a climate change perspective," said Matthews, an associate professor of civil and environmental engineering (CEE) and engineering and public policy (EPP) at Carnegie Mellon.

Weber, a Carnegie Mellon alum who is now an assistant professor in the university's Civil and Environmental Engineering Department, explained that protein sources other than beef — like chicken, fish, eggs and legumes — have fewer greenhouse gas emissions per calorie.

"Cows emit methane, a powerful greenhouse gas, during digestion. And they produce lots of manure which degrades into methane and nitrous oxide, another very potent greenhouse gas," he said. "Also, it takes more grain to create beef and dairy than it does to create chicken or farmed fish."

Carnegie Mellon's CEE and EPP programs are the reason Weber came to the university. "I love Carnegie Mellon for its commitment to interdisciplinary research and teaching, as well as its generally environmentally friendly worldview," he said.

Weber and Matthews are now developing ways for businesses to better track their products' carbon footprints. They are even calculating the greenhouse gases emitted by online music services.